I thought premium service: all the DLCs for the game in one bundle + a bunch of stuff no one really cares about.

Premium Edition: game + premium service + all the in game unlocks so you don't have to progress to the higher levels to get the guns/add ons for the guns. (although a reread of the store gives no indication to the unlocks so that may have been an initial offering bonus).

If you were going to by BF3 now I would go for the Premium Edition but that is part because I would buy all the DLC. It sort of depends on which platform you are on whether that might be reasonable, have heard a number of complaints about Armoured Kill + consoles. This is due to the limitations of the consoles, they don't have the compute power to run more than 24 players with the graphics as they are. (and even then I find the graphics a bit unsatisfying on PS3 vids vs. what I get on the PC)

Rambaldi, premium service includes weapon unlocks I think, so my statement stands.
Regarding armored kill on consoles - yes, it is a proper waste of time. Over the round we get 7 kills(well I had around 14 on average) and couple of taken flags. My battle report looks very empty. Tank superiority-you spend half of the round waiting for the tank.
Anyway that's dice with EA mentality. Last game I ever bought from those two crooks. Planet side 2 here I come.

I think there is some confusion over the term weapon unlocks, with just plain premium service you still need to get all the kills to get the scopes. I remember reading that Premium Edition came with them pre-unlocked.